The present invention relates to release coating compositions, and more specifically relates to release coating compositions which form cured coatings having a low surface tension, and which have excellent release from various tacky substances such as pressure sensitive adhesives.
It is well known that by applying a curable release coating on the surface of various substrates such as paper, synthetic resin film, paper, or synthetic fiber cloth, a material having the capability of releasing from tacky substances such as pressure sensitive adhesives is obtained.
It has also been disclosed that organopolysiloxanes can be used in curable release coating compositions. For example, in Japanese Patent Application Publication No. 63-48901 (48,901/1988) curable release coating compositions containing a vinyl functional organopolysiloxane, an organohydrogenpolysiloxane, a perfluoroalkyl compound, and platinum catalyst are disclosed. Also, in Japanese Patent Application Laid-Open No. 63-320 (320/1988), is disclosed a curable release coating composition containing fluoroalkyl functional and vinyl functional organopolysiloxane, an organohydrogenpolysiloxane, and platinum catalyst.
Although the cured coatings from these compositions show excellent release from common organic resin type tacky substances, they have inferior release properties when the tacky substance is a silicone-based tacky material containing an organopolysiloxane, and thus they have not been acceptable for use in many of these types of applications.
In Japanese Patent Application Laid-Open No. 4-185678 (185,678/1992) is disclosed a curable release coating composition containing an organopolysiloxane having fluorine atom-containing organic groups and two or more alkenyl groups, an organohydrogenpolysiloxane, a trifluorochloroethylene resin, a platinum catalyst, and an organic solvent. In this composition however, the use of an organic solvent is essential which creates problems since chlorine-based solvents such as trichloroethane are regulated for environmental protection, and aliphatic hydrocarbons such as hexane or isooctane have low flashpoints.
In Japanese Patent Application Laid-Open No. 64-74268 (74,268/1989) is disclosed a curable silicone composition containing a perfluoropolyether functional organopolysiloxane. However, the perfluoropolyether functional organopolysiloxane requires extensive time to manufacture it and therefore is expensive, and thus the final curable silicone composition is very expensive to produce.